I do not know why your Mac is identifying the DEL display as a Television.

You tried some of this but not all so please try it:

1. Reset the System

You can reset the Mac's parameter RAM and SMC.

2. Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

    Start up in [Safe Mode][1].
    From the Apple () menu, choose System Preferences.
    Choose Displays from the View menu to open the preferences pane.
    Select any resolution and refresh rate that your display supports.
    Restart your computer.

EDIT: Well we were right about the TV mode. here is a very, very long discussion and some possible fixes but I can not try them since i (luckily) do not have that monitor.

I do not know why your Mac is identifying the Dell display as a television.

You tried some of this but not all so please try it:

1. Reset the System

You can reset the Mac's parameter RAM and SMC.

2. Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

• Start up in Safe Mode.
• From the Apple () menu, choose System Preferences.
• Choose Displays from the View menu to open the preferences pane.
• Select any resolution and refresh rate that your display supports.
• Restart your computer.

EDIT: Well we were right about the TV mode. here is a very, very long discussion and some possible fixes but I can not try them since i (luckily) do not have that monitor.

I do not know why your Mac is identifying the DEL display as a Television.

You tried some of this but not all so please try it:

1. Reset the System

You can reset the Mac's parameter RAM and SMC.

2. Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

    Start up in [Safe Mode][1].
    From the Apple () menu, choose System Preferences.
    Choose Displays from the View menu to open the preferences pane.
    Select any resolution and refresh rate that your display supports.
    Restart your computer.

I do not know why your Mac is identifying the DEL display as a Television.

You tried some of this but not all so please try it:

1. Reset the System

You can reset the Mac's parameter RAM and SMC.

2. Reset the resolution

Start by resetting the Mac's parameter RAM. If the display does not come up, was previously set to an unsupported resolution, and still results in no video:

    Start up in [Safe Mode][1].
    From the Apple () menu, choose System Preferences.
    Choose Displays from the View menu to open the preferences pane.
    Select any resolution and refresh rate that your display supports.
    Restart your computer.

EDIT: Well we were right about the TV mode. here is a very, very long discussion and some possible fixes but I can not try them since i (luckily) do not have that monitor.